The 2239 has 1/8" (3.5mm) microphone input and stereo line level phono jack inputs. The 2239 digitizes the audio input into 16-bit samples at 48KHz rate. The microphone input is copied to both channels, the two line inputs remain in respective channels. The digitized stereo audio is transmitted across fiber and received at the 2239. The 2239 converts the digitized audio back to analog. The 2239 has 1/8" headphone jack, line level phono jacks, and speaker phono jacks.

The 2239 has line input volume adjustment to maximize the use of the digitized channel and speaker/headphone volume adjustment. The 2239 has optical signal loss LED. Local and remote 2239 have mute buttons.